Hardening metals



UNITED STATES PATENT OFFICE.

CHARLES M. DABCLL, OF NEW LONDON, CONNECTICUT.

HARDENING METALS.

i 4 SPECIFICATION forming part of Letters Patent No. 255,725, dated March 28,1882.

Application filed August 25, 1881. (No specimens.)

To an whom it may concern:

Be it known that I, CHARLES M. DABOLL, of New London, in the county of New London and State of Connecticut, have invented certain new and useful Improvements Relating to Hardening Metals, of which the following is a specification.

I'have experimented on what are known as roller-bushings in the sheaves of pulleyblocks for use on shipboard and in other situations. The usefulness of these bushings depends largely upon the maintainin g of the sizes and proportions of the members of the complex structure. Economy requires that the whole be made cheaply. I make all the parts of common cast-iron, cast in sand in the ordinary manner, with the smallest cost and with the moderate hardness due to ordinary castings thus made. I finish the parts while in the ordinary soft condition. Then, without any long process and without requiring expensive labor, I harden the finished castings without distorting orwarping them. The surface produced by the treatment is a good protection against oxidizing influences.

My hardening is effected more quickly and cheaply than case-hardening, and the hardness is different. The castings are hardened quite through. It will of course be understood that the posts which traverse the spaces between the rings and hold them together are made of metal which will rivet. The other parts-rollers, shell, rings, and, if desired, the entire sheave-may be cast-iron, accurately finished and hardened. I believe that for all the purposes for which chain and rope sheaves are required the parts will maintain their exact size and condition indefinitely.

All the parts are cast of ordinary iron, and then reduced to the exact size and form by tools acting on it in a soft condition.

I employ a hardening-trough containing a solution compounded as follows: Forty gallons of pure water, fifty pounds of common rock-salt, two pounds of saltpeter, two pounds of cyanide of potassium, five pounds of the ordinary sulphuric acid of commerce. The solution should be kept cold or at as low a temperature as the active use in cooling large numbers of small castings will allow.

Care should be taken to heat the parts separatel y or to so support them as not to distort the forms or bruise or in any wise injure the surfaces which require to work together. They should be plunged into the solution endwise.

v Castings one and one-halfllg) inch through have by my treatment been hardened entirely through, and I believe much larger ones can be similarly hardened quite evenly through to a considerable depth at the instant of immersion. The nature of the metal is materially changed by the process. They should be allowed to lie in the solution a few minutes after moment of cooling, but the solution affects thesurface more thoroughly by being allowed to remain. 1t contributes to give more perfectly my operation. ing-bath they are soaked a considerable time in water containing lime to neutralize any acid remaining in the pores; They are then dried, applied together, inserted in the sheave, and introduced in the block.

serves as a fixed axis, is of my hardened castiron, similarly made and hardened.

It is important that all the elements be employed, but the proportions may be varied within considerable limits. I esteem the cyanide of potassium especially important. The proportion thereof should not be much less than above indicated. The cost of the whole expensive furnaces or boxes or packing are required. The whole may be operated with the ordinary tools and appliances of a small foundry and machine-shop.

The body of the sheave may be of any material-composition, cast-iron, galvanized, or lignum-vitae or other hard wood.

The shell may have a flange and fasteningrivets. The hardened bushing may be inserted in the metallic sheave by driving, pressing, pinning, .or any other ordinary or suitable way. When the body of the sheave is of iron the shell may be dispensedwith and the body of the sheave itself cast in the proper form, and milled or turned out to receive the rollers directly. In such case the entire sheave should be hardened in my solution. It will be underwith proper apparatus to move each rapidly 6) the cooling. Thehardeningiscompleted atthe the fine blue-black oxide, which is one result of I 011 removal from the harden- The pin, which is fixed in the block and is insignificant. Little time is consumed. No

stood that the block may be Wood or metal,

cyanide of potassium, combined in about the proportions herein specified.

In testimony whereof I have hereunto set my hand, at New London, Connecticut, this 15 20th day of August, 1881, in the presence of two subscribing witnesses.

CHARLES M. DABOLL.

and widely varied as to f0rm,nu mber of sheaves, mode of strapping, &c.

The pin may be cylindrical steel, hard iron, or any other ordinary material.

The articles herein described as hardened will be made the subject of a separate applica- I tion for patent.

I claim as my invention- Witnesses: The hardening solution described, com posed CHARLES ALLISON, of'water, sulphuric acid, salt, saltpeter, and A. H. AVERY. 7 

